The present invention relates to a device for the administration of an active agent to a host. The device allows for topical administration to the host or administration through the skin or mucosa of the host over a period of time.
Transdermal administration systems are known in the art. For example, Ciba-Geigy's Transderm.RTM.-Nitro and Transderm.RTM.-V systems have been approved for transdermal administration of nitroglycerin and scopolamine, respectively.
Other similar devices are described, for example, in U.S. Pat. Nos. 3,598,122; 3,598,123; 3,734,097; 3,742,951; 3,797,494; 3,926,188; 3,996,934; 4,031,894; and 4,060,084.
Characteristically, the controlled continuous metering devices known before the present invention contained a backing member which defined the outer surface of the device, a membrane was sealed to the backing member and created a reservoir therebetween containing the active agent, and an active agent permeable adhesive layer on the membrane defined the other face surface. Alternatively, the active agent, rather than being in one separate reservoir, is contained in a plurality of microcapsules distributed throughout the permeable adhesive layer. In either case, the active agent is delivered continuously from the reservoir or microcapsules through a membrane into the active agent permeable adhesive, which contacts the skin or mucosa of the recipient.
In order to insure a constant, complete and continuous seal of the device to the skin or mucosa, and to insure the predetermined, controlled transport of the active agent to the skin or mucosa, the active agent permeable adhesive layer in the prior art devices has been made to extend substantially to the rim, or edge, of the surface of the backing member. Thus, in such devices, substantially the entire face, or surface, in contact with the skin or mucosa consisted of the active agent permeable adhesive. While such devices have a number of advantages, including a continuous seal, certain potential disadvantages are apparent.
For example, unless due care is exercised, contamination of the drug permeable adhesive layer can easily occur by finger contact when a user applies the device to the skin. Thus, where the fingers are sufficiently contaminated with perspiration, body oils and foreign matter, the resulting contamination of the active agent permeable adhesive may adversely affect the permeable nature and/or the adhering ability of the adhesive to the skin. This, in turn, can adversely affect the desired predetermined rate of transport of the active agent to the recipient.
Moreover, finger contact with the active agent permeable adhesive will contaminate the finger with the active agent. This is undesirable. For example, where the active agent is an eye irritant such as scopolamine, subsequent contact of the contaminated finger to the eye may result in irritation.
Further, since the active agent permeable adhesive is ordinarily present on the entire face in contact with the skin, the active agent and/or other formulation components may ooze from the sides, or rim, of the device, for example, during storage or during use.